The present invention relates to a device for indicating, defining or fixing the positions of printed circuit cards or boards, with respect to their connectors. It more particularly applies to any functional system of printed circuit cards carrying electrical or logic components, in which the different positions which can be occupied by these cards relative to their connectors must be indicated during the operation of the system. This serves to reduce the period during which the system is stopped during the removal or reinsertion of a card with respect to its connector.
It is known that a printed circuit card or board carrying electrical and/or logic components has a terminal surface carrying conductor elements able to enter into electrical contact. The outputs of the electrical connectors make it possible to interconnect the various cards or connect these cards with the cards of another system. The corresponding conductors of the connector and card can occupy three relative positions, a first position called the "safe" contact position between the corresponding conductor elements of the connector and the card, this being the position for which the card is correctly installed relative to its connector and for which it makes it possible to affirm that the operation of the system of cards is correct. One or more of these cards can also occupy a so-called intermediate second position, for which the contacts between the corresponding conductor elements of the connector and the card are "not safe". Thus, when a card is being inserted or removed with respect to its connector, it is not possible to affirm that the operation of the system takes place under satisfactory conditions, because the contact between the conductor elements of the card and of the connector cannot be looked upon as correctly ensured. Finally, there is a third position for one or more cards relative to their connectors. This is the position when one or more cards are completely removed from the connector corresponding thereto, no contact being any longer established between the corresponding conductor elements of the card and of the connector.
At present, there is no device making it possible to automatically indicate within a system of printed electrical circuit cards carrying electrical and/or logic components, the different positions of said cards relative to their connectors.
In any functional system requiring a permanent operation, the removal of a card leads to a relatively long immobilization thereof. To prevent this, this system is generally duplicated, so that it is not necessary to interrupt for an excessively long time one of the systems, in the case of removing one or more cards from the other system. This is generally the case in printed circuit card systems carrying memories and microprocessors. In such systems, when it is necessary to remove a card for a random intervention, various operations have to carried out by the technician in a non-automatic manner. He must firstly supply instructions for protecting data contained in the memories, then must place all the processors or microprocessors in the hold position and then, if necessary, must interrupt the electrical power supplies of the cards in the system for which an intervention is necessary. Finally, it is necessary for the technician to initialize the operation of the duplicated system. These non-automatic interventions take a long time.